• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6A
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• pp.499-509
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• 2005

The capacity of Satellite DMB(Digital Multimedia Broadcasting) system is limited mainly by the interference. So, to achieve the expected performance of Satellite DMB system and to minimize the interference from other Satellite DMB system, ACI(Adjacent Channel Interference) should be considered carefully. Satellite DMB system uses the Gap-filler for effective transmission in terrestrial environment, and the Gap-filler can use direct amplification or frequency conversion to satisfy the specific requirements. Therefore, amplified signal causes several effects on interference between System A(Eureka 147 DAB) and System E(ISDB : Integrated services Digital Broadcasting). In this paper, by using the outcome of system-level simulation considering the results of link-level simulation, we analyze the interferences between System A and System E under practical situation based on the exact parameters of ITU-R BO. 1130-4. We also propose the appropriate level of guard band and Cell Radius to optimize system capacity by adapting the spectrum mask given in the spec. and utilizing the interference analysis between System A and System E.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.32-39
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• 2012

In this paper, the implementation of location based services (LBS) using S-DMB (satellite-digital multimedia broadcasting) system was proposed. In S-DMB System, the frequency of transmitted signal is about 2 GHz which has a characteristics of strong straightness but weak diffraction so that there are many shade areas such as indoors and underground spaces. Therefore the signal transmitted from the satellite should be retransmitted by the earth repeaters called as gap filler. Because each gap filler has its own identification value, the gap filler ID introduces the area in which the gap filler was installed. Generally, the 51st data symbols of S-DMB pilot signal transmitted from the satellite are padded by dummy value and gap filler ID is embedded in this pilot symbol by the gap filler when S-DMB signals are retransmitted by gap fillers. So using gap filler ID of S-DMB system, LBS such as region registration, distance and time to destination, alarm of local area information could be implemented. In the experiment to prove the performance of the proposed LBS system using the gap filler ID of the S-DMB system, the firmware of S-DMB chip composing of RF and baseband parts was lightly modified so that application processor was able to manipulate the gap filler ID and the its related regional information.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.521-521
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• 2015

This study evaluated the gap filler radar as an implementation of the 1.5 km CAPPI data in Korea. The use of the 1.5 km CAPPI data was an inevitable choice, given the topography of the Korean Peninsula and the location of the radar. However, there still exists a significant portion of beam blockage, and thus there has been debate about the need to introduce the gap filler radar (or, the gap-filler). This study evaluated the possible benefits of introducing gap-fillers over the Korean Peninsula. As a first step, the error of the radar data was quantified by the G/R ratio and RMSE, and the radar data over the Korean Peninsula were evaluated. Then, the gap-fillers were located where the error was high, whose effect was then evaluated by the decrease in the G/R ratio and RMSE. The results show that the mean values of the G/R ratio and RMSE of the 1.5 m CAPPI data over the Korean Peninsula were estimated to be about 2.5 and 4.5 mm/hr, respectively. Even after the mean-field bias correction, the RMSE of the 1.5 km CAPPI data has not decreased much to be remained very high around 4.4 mm/hr. Unfortunately, the effect of the gap-filler on the 1.5 CAPPI data was also found very small, just 1 - 2%. However, the gap-filler could be beneficial, if the lowest elevation angle data were used instead of the 1.5 km CAPPI data. The effect of five gap-fillers could be up to 7% decrease in RMSE.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.950-955
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• 2005

This paper describes an intelligent filler wire feeding device which can control 3- dimensional seam tracking and the filler wire speed by measuring the gap position and the joint gap width in laser welding. By means of visual sensor controlled filling the missing material into the joint gap and 3 dimensional seam tracking, lineup errors from manufacturing tolerances and the repeatability of lineup jigs and weld robot can be balanced and at an even seam quality which avoids weld defects. In this paper, we assessed weld quality in 2mm sheets of A16061 which had various gap width by using the intelligent filler wire feeding device.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.27-40
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• 2020

In this paper, we investigate the correlation between the amount of English sentences that Korean English learners (L2ers) are exposed to and their sentence processing patterns by examining what Long Short-Term Memory (LSTM) language models (LMs) can learn about implicit syntactic relationship: that is, the filler-gap dependency. The filler-gap dependency refers to a relationship between a (wh-)filler, which is a wh-phrase like 'what' or 'who' overtly in clause-peripheral position, and its gap in clause-internal position, which is an invisible, empty syntactic position to be filled by the (wh-)filler for proper interpretation. Here to implement L2ers' English learning, we build LSTM LMs that in turn learn a subset of the known restrictions on the filler-gap dependency from English sentences in the L2 corpus that L2ers can potentially encounter in their English learning. Examining LSTM LMs' behaviors on controlled sentences designed with the filler-gap dependency, we show the characteristics of L2ers' sentence processing using the information-theoretic metric of surprisal that quantifies violations of the filler-gap dependency or wh-licensing interaction effects. Furthermore, comparing L2ers' LMs with native speakers' LM in light of processing the filler-gap dependency, we not only note that in their sentence processing both L2ers' LM and native speakers' LM can track abstract syntactic structures involved in the filler-gap dependency, but also show using linear mixed-effects regression models that there exist significant differences between them in processing such a dependency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.93-97
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• 2007

In this paper a new clock generation scheme for TDM-CDM converter in the Gap Filler for satellite DMB systems has been proposed. The scheme uses the frame sync signal from the Ku band TDM receiver to lock the VCXO which provides the system clock for the TDM-CDM converter. The locking algorithm can be easily implemented in the FPGA, so that no separate circuitry is needed as in conventional PLL. With a stable OCXO, The scheme can be used to generate the reference clock to the local oscillator for RF parts.

• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.22-28
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• 2013

In this paper, new LBS (location based service) are proposed using conventional DMB (digital multimedia/mobile broadcasting) system. LBS applications are proposed that can be suitable for the subway and ground transportation based on S-DMB (satellite-DMB) and T-DMB (terrestrial-DMB) respectively. In the shaded area such as subway, the broadcasting signal transmitted from the satellite of S-DMB system should be retransmitted by the earth repeater called the gap filler and each gap filler has its own identification value called the gap filler ID which introduces the area in which the gap filler was installed. Therefore, the LBS can be implemented by using the gap filler ID of S-DMB on the subway in which the GPS (global positioning system) can't be received. Unlike the LBS on the subway, the combination of T-DMB and DGPS (differential GPS) will be introduced as a way for ground transportation. Generally, DGPS has been designed to compensate the position value calculated from the GPS signal so that positioning error of about 1 meter can be obtained by using DGPS information. T-DMB system transmitting DGPS signal will be expected to be commercial in Korea and, if using DGPS information transmitted through T-DMB network, LBS with more precise positioning than GPS alone can be implemented in the ground vehicles.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.7 s.184
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• pp.59-66
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• 2006

In laser welding, automatic seam tracking is important to adjust the laser head position in real time as it moves along the seam. Also if the joint gap is occurred, filling the missing material into the joint gap is necessary to prevent welding defects and bad welding quality. In general, the joint gap width is not constant along the seam due to a variety of reason. So it is essential to control the filler wire speed into the joint gap to acquire good welding quality. This paper describes an intelligent filler wire feeding device which can control 3-dimensional seam tracking and the filler wire speed by measuring the gap position and the joint gap width in laser welding. We call this device as Smart Micro Control system(SMC). To achieve this objective, we assessed weld quality in 2mm sheets of A16061 which had various gap width by using the developed device. From the experimental results, It was found the possibility that the developed device could be used in welding various 3-dimensional structures.

• Steel and Composite Structures
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• v.26 no.2
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• pp.139-150
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• 2018

In this paper, two kinds of buckling restrained braces (BRBs) are designed to improve the mechanical properties and fatigue life, the reserved gap and viscoelastic filler with high energy dissipation capacity are employed as the sliding element, respectively. The fatigue life of BRBs considering the effect of sliding element is predicted based on Manson-Coffin model. The property tests under different displacement amplitudes are carried out to evaluate the mechanical properties and fatigue life of BRBs. At last, the finite element analysis is performed to study the effects of the gap and viscoelastic filler on mechanical properties BRBs. Experimental and simulation results indicate that BRB employed with viscoelastic filler has a higher fatigue life and more stable mechanical property compared to BRB employed with gap, and the smaller reserved gap can more effectively improve the energy dissipation capacity of BRB.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.19-22
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• 2004

위성 DMB(Digital Multimedia Broadcasting)는 위성을 통하여 이동 흑은 고정 무선 가입자 수신기에게 비디오 방송 및 정지화상 CD 음질의 오디오 방송과 각종 데이터 서비스와 같은 Multimedia 서비스를 제공하는 서비스이다. 향후 새로운 사업으로 다양한 부가가치를 이끌어 낼 것으로 기대를 받고 있다. 우리나라의 경우 위성 DMB기술기준으로 System E방식이 선정되었다. 본 논문에서는 위성DMB 서비스 의 음영지역을 해소하기 위해 사용되는 재생중계방식의 중계기인 Gap Filler 개발에 대해 기술한다. System E용 Cap Filler용 보조 방송의 전송 방식 선정과 보조방송에서 주 방송으로의 변환 기법, Gap Filler 망설계시에 고려해야 할 사항 등에 대해 기술한다.